ok, I think I know whats wrong.
when you mount the sway bar, the bar should be as level to the ground as possible. if the bar is pointed in a downward position, then it will flip like what happened to you.
now it would be to your benifit to get adjustable endlinks. This should elimiate your troubles.
going back the reinforced tabs...look at these pics. its hard to see in this pic, but if you look where the bushing mount, you will see a small reinforced tab. this is the only difference between the msp and stock p5 subframe.
msp subframe:
now, look at this one (P5)
pay no pay no attention to ms paint markings lol
now, it should look like this when done. notice how the bar sits level with the ground.
does this make sense?